Wednesday, December 28, 2011

If all the Phys Ed columns published this year have a single message, it is that now is a fine time to own a body. The diverse exercise-related experiments published in 2011 and covered in this space each week suggest that it’s possible to retain your cognitive powers, muscle mass, running speed and waistline, even as you age, and that a little exercise can go a long way in terms of physiological benefit. Recent, important science even tells us that coffee, chocolate and beer enhance exercise performance, which is fortunate, since I have no plans to give up any of those. As most of us prepare our exercise resolutions for 2012, now seems an ideal time to review the past year in fitness science and the lessons it contained, both encouraging and cautionary.

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Perhaps the most inspiring exercise science published in 2011 involved the effects that working out can have on the brain. By studying both lab rodents and people, scientists this year showed that exercise increases cognitive sharpness, even if the amount of exercise is small. In a representative experiment involving mice, which I wrote about in September, scientists at the University of South Carolina found that the equivalent of about 30 minutes of jogging a day changed the animals’ brain cells at a molecular level. After a few months of running, their neurons contained more mitochondria, a cell component that produces energy, than did the neurons of sedentary mice. In effect, their brain cells had become more robust and physically fit, thanks to the jogging.

Similarly, other studies published this year found that even in volunteers who were not distance runners or mice, activity significantly improved cognitive function. One fascinating study of elderly Canadians that I wrote about this summer showed that those who regularly walked around the block, gardened, cleaned the house, cooked or otherwise remained active without formally exercising, scored much better on tests of memory and other mental skills than older people who were almost completely inactive.

This study and the many others now linking activity and improved mental functioning represent “a wake-up call,” Dr. Eric Larson, the vice president of research at Group Health Research Institute in Seattle and author of an editorial that accompanied the study, told me.

“None of us wants to lose our minds,” he said — a sentiment with which I fervently agree — so we “have to find ways to get everybody moving.”

One means might be to direct people to the most popular column I wrote this year, in terms of both the number of page views and the number of comments, about the effect of exercise on aging. In the study highlighted in that column, Dr. Mark Tarnopolsky, a professor of pediatrics at McMaster University in Hamilton, Ontario, took rats bred to age at an accelerated rate and had them start running.

After a few months, by which time the non-running control rats were frail, bald and dying, the runners still had virtually all of their youthful muscle mass, balance, mental acuity and fur and, unlike the sedentary animals, had not developed shrinkage in their hearts, brains or gonads. I have rarely skipped an exercise session since reading that study, and am happy to report that I still have a full head of fur.

Not all of the exercise science this year was quite so encouraging, however. Another column that inspired considerable interest and comments involved several new studies intimating that too much running might – and I would stress the word “might” – produce scarring or other damage in the heart. In one study, M.R.I. scans of a small group of lifelong elite male endurance athletes found signs of scarring in some of the men’s heart muscles.
A separate study of rats that had undergone the equivalent of years of marathon training showed similar signs of scarring within their hearts.

But these results, although certainly provocative, are preliminary and may turn out to be meaningless, as the scientists who conducted the studies acknowledge. There is no evidence that heart muscle scarring, if it occurs, leads to heart problems. And as Dr. Paul Thompson, the chief of cardiology at Hartford Hospital in Connecticut and an expert on sports cardiology, told me, “Too much exercise has not been a big problem in America. Most people just run to stay in shape, and for them, the evidence is quite strong that endurance exercise is good” for the heart.

Just as the evidence is increasingly strong that it is good for your brain, muscles, mitochondria and gonads.

Which is why I plan to continue running — and biking, hiking, walking, gardening and weight training — in 2012, although I may leave the housecleaning to my husband. In reviewing the year in fitness, in fact, what struck me most strongly was that, although this column covers science, it is also sneakily about me. I’m a middle-aged lifelong exerciser with an increasingly leaky memory and sometimes-wavering resolve. I’ve found inspiration and encouragement in the fitness science this year, although I do wish that it could have discovered that typing constitutes a workout. At least fidgeting counts.